Camera shutter mechanism



March 9, 1954 G. N. SMITH CAMERA SHUTTER MECHANISM riginal Filed June 16. 194? 10 Sheets-Sheet 1 STOP F'OC S INVENTOR. Gordon N. Smii/z March 9, 1954 G. N. SMITH 2,671,390

CAMERA SHUTTER MECHANISM Original Filed Jpne 16, 194'? 10 Sheets-$heet 2 4o '65 /21 57 I171 MZ I53 400 M401 PM, i

'f INVENTOR. F- M4 47 Gordon N, Smith A BY 9 mvwzam.

March 9, 1954 G. N. SMITH CAMERA SHUTTER MECHANISM 10 Sheets-Sheet 5' Original Filed June 16, 1947 INVENTOR. GORDON /V. 6M/7'H %m 104mg;

March 1954 G. N. SMITH 2,671,390

CAMERA SHUTTER MECHANISM Original Filed June 16, 194';

l0 Sheets-Sheet 4 g Y 4 'INVENTOR.

GORDON N. \SM/TH March 9, 1954 G. N. SMITH CAMERA SHUTTER MECHANISM 1 o Sheeis-Sheet 5 Original Filed June 16, 1947 mxi ' INVENTOR.

GORDON N. SMITH km W! -M;

March 9, 1954 s l-i 2,671,390

I Q CAMERA SHUTTER MECHANISM Original Filed June 16,194?

10 Sheets-Sheet 6 14 I INVENTOR.

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March 9, 1954 G. N. SMITH CAMERA SHUTTER MECHANISM l0 Sheets-Sheet '7 Original Filed June 16, 1947 INVENTOR.

Gordon Jmi H1 G. N. SMITH CAMERASHUTTER MECHANISM March 9; 1 954 10 Sheets-Sheet 8 Original Filed June 16,1947

INVENTOR. GORDON N. 6M TH March 9, 1954 G N v T|-| 2,671,390

CAMERA SHUTTER MECHANISM Driginal Filed June 16, 1947 10 Sheets-Sheet 9 I I 274 I6 /0 6 INVENTOR. Gore oh /v. 5mm,

March 9, 1954 rr 2,671,390

CAMERA SHUTTER MECHANISM Original Filed June 16, 1947 10 Sheets-Sheet 10 INVENTOR. Goya/on /V. \smz'fh Patented Mar. 9, 1954 UNITED STATES ATENT OFFICE CAMERA SHUTTER MECHANISM Gordon N. Smith, Portland, 0reg., assignor, by mesne assignments, to Sawyers Inc., Progress, 0reg., a corporation of Oregon 3 Claims. 1

This application is a division of my copending application Serial No. 754,961, filed June 16, 1947, now Patent No- 2,553,015,, issued May 15, 1951.

The parent application identified above is directed toward shutter controlling mechanism whereby a pair of shutters may be controlled and operated to make exposures at a fixed high speed, at an infinitely variable plurality of other high speeds, or at timed speeds under manual or bulb control. The present divisional application is directed toward the specific shutter mechanism embodied in the camera.

The present invention has for its principal object to provide a pair of superimposed, movable shutters having apertures therethrough which, when overlapped and aligned with the camera lens, permit the passage of light to the interior of the camera, spring means individually associated with each of the shutter blades for causing them to move from a set to a released position, and means for returning the shutters to set.

position, said apertures being so shaped and positioned that when the shutters are in set position one of the shutters completely obscures the lens, and when said one shutter has been released, followed by the other shutter in timed relation, either mechanically or manually controlled, the lens will be uncovered to permit passage of light to the film.

A further object of the present invention is to provide a camera with a guillotine-type shutter mechanism including a pair of shutter blades, in which the blades do not lie between the lens elements, by reason of which the lens assembly is more easily manufactured and the relationship of the various elements of the lens to each other may be accurately maintained.

Another object of the present invention is to prevent shutter bounce in a camera having a guillotine-type shutter by causing the shutter blades to strike means so positioned and arranged that the-shutter blades although adjacent each other cannot be thrown. back to cause double exposures.

Another object of the present invention is to provide means 'for latching both shutter blades by e primary latch prior to the initiation of action of the escapement mechanism in order to eliminate the possibility of releasing the secondary shutter blade of a guillotine-type shutter by impact due to inertia of the lever for effecting the release of the secondary latch if the camera should be subjected to a sharp blow o to some unusual movement, This object of the present invention is achieved. by transfcrringcontrol' of the secondary blade from a, primary latch to a secondary latch after initiation of the escapement movement.

A further object of the present invention is to insure that all lost motion and backlash which might contribute to erratic shutter timing is eliminated by having the escapement mechanism in motion before releasing the primary shutter blade.

A further object of the present invention is to provide improved shutter blade controlling. means including a timer cam movable to a plurality of selectable positions in one of which positions the blades are released simultaneously and in another of which positions th y blades are released in timed relation to each other.

The foregoing and other objects and advantages of the present invention will be more readily understood from inspection of the accompanying drawings taken in connection with the following specification, wherein like numerals refer to lik parts throughout.

In the drawings Fig. 1 is a plan View looking down upon the top of a stereoscopic camera, having the present invention incorporated therein;

Fig. 2 is a view in elevation of the rear surface of the camera;

Fig. 3 is a view in elevation of the front of the camera;

Fig. 4 is a view in elevation of the right end of the camera;

Fig. 5 is a partially schematic view of the major portion of the shutter release and timing mechanism in set position. It is to be appreciated that various portions of this mechanism overlap but occupy various levels, hence some portions are drawn in skeleton outline;

Fig. 6 is a view illustrating the major portion of the shutter release and timing mechanism just after being released for taking a high speed exposure;

Fig. '7 illustrates the shutter release and timing mechanism just after being released to take an exposure of the longest possible adjustable duration or at the slowest fixed speed;

Fig. 8 illustrates the shutter release and timing mechanism when released to take a time exmechanism at the termination of a time exposure with the parts in the position they would assume corresponding to the bulb closed position of a standard camera;

Fig. 10 is a partial vertical section taken substantially from the plane indicated by the line 3 I-I0 (center of Fig. 5) illustrating the exposure time selecting mechanism, selecting knob and xposure speed dial;

Fig. 11 is a partial horizontal section taken substantially along line II--II of Fig.

Fig. 12 is a plan view of the escapement mechanism with the timer cams illustrated in dash line for the purpose of clarity;

Fig. 13 is a plan view looking down upon the trip mechanism, along line I3I3 of Fig. 14, with all other parts eliminated for clarity;

Fig. 14 is an end elevation taken from the plane I4I 4 of Fig. 13;

Fig. 15 is a plan view illustrating the reset mechanism with the parts illustrated in the set position corresponding to Fig. 5;

Fig. 16 is a view similar to Fig. 15 showing the reset mechanism after the shutters have been tripped, the, parts being shown in positions corresponding to Fig. 6;

Fig. 17 is a similar view showing the reset mechanism in operation to reset the shutters and shutter release mechanism, with various parts shown in dotted line at the commencement of a resetting operation and in full line in the course of a resetting operation;

Fig. 18 is a rear view of the front shutter blade;

Fig. 19 is a rear view of the rear shutter blade;

Fig. 20 is a similar view showing the shutter blades superimposed and in the positions they occupy at the end of a resetting movement with the resetting mechanism corresponding to the position shown in full line in Fig. 17;

Fig. 21 shows the shutter blades in the positions they occupy when the camera is set, with the resetting mechanism in position corresponding to that illustrated in dash line in Fig. 17;

Fig. 22 illustrates the shutter blades in the positions corresponding to the commencement of a time exposure;

Fig. 23 illustrates the shutter blades in the positions they occupy at the end of an exposure and Prior to the operation of the reset mechanism;

Fig. 24 is a vertical section taken through the shutter blades and the shutter blade case substantially along the line 24--24 of Fig. 15;

Fig. 25 is a partial vertical section on an enlarged scale taken substantially along line 25-25 of Fig. 24;

Fig. 26 is a plan view of the synchro-switch with related mechanism shown in skeleton outline; and

Fig. 27 is a partial bottom view showing the synchro-switch adjustment screw.

Although all portions of the mechanism herein disclosed function in conjunction with each other various portions thereof will be separately described in order more clearly to describe the operation'of the camera. These portions will be set aside under appropriate subtitles.

Shutter release and timing mechanism The shutter releasing and timing mechanism is mounted upon and between a pair of plates, the bottom plate I5 of the camera and an intermediate plate I 43. The plate I43 is mounted upon a plurality of bosses I54extending upward from the bottom plate I5, so that there is a space between the plates. A primary shutter latch 9 is mounted on the upper surface of plate I43 and a secondary shutter latch I0 is mounted on the lower surface of plate I43. The latches extend beyond the plate a sufllcient distance #9 engage in slots I06 and I6! (Fig. 20) of the front and rear shutter blades. The shutter consists of a pair of shutter blades 1 and 3 movable from left to right by shutter blade springs 2 and 4 respectively (Fig. 24). When the shutter blades are set at the left of their travel the latch 9 holds them in this position, at which position apertures I36 in the rear blade 3 are aligned with the lenses 98 and 99, but light is prevented from reaching the film by the blade I whose apertures I35 are to the left of the lenses and not in line with them. The latch I0 is normally locked by the latch pawl I I which is also pivoted beneath plate I43. The shutter blade I never bears against latch I0, and blade 3 normally does not bear against latch I0, which is a secondary latch or a timing latch. Latch I0 is released from latch pawl II through the operation of a main lever 8 (Figs. 5 to 9) which may be unintentionally moved due to impact or inertia effect, thus causing the secondary latch pawl I I to move out of engagement with the secondary latch I0, but as soon as such a transient phenomenon has caused the latch I0 is again retained by the latch pawl II. A light spring I39 holds latch I0 in a counterclockwise direction to be engageable by pawl II. Latch 9 normally holds both shutter blades I and 3. Latch 9 is also lightly urged counterclockwise by a spring I38. When latch 9 is released, as will presently appear, the stronger spring 2 operating upon the blade I overcomes the weaker spring I38 and causes latch 9 to be moved in a clockwise direction to release blade I, which thereupon moves so as to bring its apertures I35 in line with the lenses, and since the apertures I36 in blade 3 are in line with the lenses light is permitted to reach the film. Latch I0 has now engaged blade 3 due to its having been released by latch 9 and moving slightly to the right. Latch III will be released at a later period, as will appear, so as to cause the apertures I36 to move to the right beyond the lenses, thus cutting off the light from the film. It may be seen that the timing of releasing latches 9 and I0 times the exposure of the film.

The latch 9 is retained in latching position by a hook 200 on a primary latch pawl I34 which is pivoted for convenience on a timing cam shaft 49. The primary latch pawl I34 extends toward the right end of plate I43 and carries a lever drive pin 46 at its right end which extends downward through an irregularly shaped opening 20I in the plate I43. The primary latch pawl I34 also extends toward the left end of plate I43 and is provided with an offset extension which carries a primary latch pawl reset stud 51. When the primary latch pawl I34 moves counterclockwise about its pivot 49, the hook 200 moves out of engagement with the latch 9 to permit the shutter blade I to snap toward the right.

The latch pawl I34 is retained in the position illustrated in Fig. 5, which is in set position, meaning that the camera is set to take a picture. In this position its right end is engaged by the downwardly turned end of a release lever pawl .I3 pivoted on a release lever pivot 202 mounted on plate I 43. The release lever pawl is provided with a downwardly turned tab 203 which engages a shoulder on a release lever I6 extending toward the right of the plate I43 and pivoted at 202.

The left end of lever I5 extends over plate I43 and has a tab 204 passing through a hole 205 in the plate I43. to hold the release lever in the position illustrated A release lever spring I51 tends tnlEFig. :5. 'whentheiever I6 sis'ashiftedclockwise'itotheposition :showni'in'Fig. 56 the shoulder thereon engaging the :tab 52 ,08 rocks the :release lever pawl I3 from engagement with the end of :primary latchipawl I134. .Astrong :spring I4 having ;one .end embracing a stud .261 on plate I43 is tensioned .about timing camshaft 49 and hooked around the lever drive pin 46 on the primary latch pawl I 34. When the release "lever IG is thus moved out of the way the spring :I4 moves theprimary' latch pawl I34 in acounterclockwise direction. Afterit moves far enough the hook 200 is disengaged from the latch '9 and the shutter blade I snaps to the right. Itis to be appreciated that, since the shutter blades are not shown in Figs. '6 to 9 inclusive, the latches 9 01' It, as the case may be, are not correctly illustrated in some cases since they should be rocked clockwise by the shutter blades. The

reason for-illustrating thelatches as shown is to emphasize the timing action of the'release mechanism.

in "order --to release the secondary latch Ii) means are provided to rock the secondary latch pawl -I=I counterclockwise about-its pivot against the tension of a spring I46. Such means comprises a hook provided on the lower surface of the left end extension 2-10 of main lever '8 which normally bears lightly against the end of latch pawl II or may float adjacent thereto. The left end 210 is'twisted to lie in a vertical plane, so that after releasing pawl II it bears against the edge of plate 143. The lever ii is afloating lever not having any fixed pivot. It is mounted beheath the plate I43 and'is pivoted to the primary release :pawl "I34 by'means of the lever .rive pin 46 extending through the plate clearance hole cm.

Motion of pawl I34 and main lever 8 is transmitted to the escapement by a main lever slot lit-engaging a sector gearstud 25 mounted upon and projecting upwardly from a sector gear 24 carried by a sector gear pivot "I41 journalled in the two plates IS-and I43.

"The other mechanism :for controlling the'manher of movement of the main lever 8 comprises a timing cam 48 splined to the timing cam shaft 49. The timing cam has a major radius portion 450 (Fig. 11) extending for a few degrees. This is followed by a slight step l ai which marks the commencement of a spiral surface I52, extending for substantially three-fourths of the periphery ofthe cam. This is followed by :a further step -leading to a minor radius I 56 extending for a few degrees, the points of minor and major radius being joined by a straight surface. The relative position of cam =48 may be fixed by rotating the shaft 49, the desired location thereof being indicated by a dial as will presently appear.

The sector stud 25 engaged'in slot I 48 acts to translate the relatively linear motion'of slot M8 to rrota-ry motion of the sector gear 24. In so doing the movement of the right end of main leverll is retarded due to the drag-of an escapern'ent mechanism driven by the sector gear 24. The stud 25 and slot I48 maybe called a flexible coupling. The direction of movement of any portion of main lever '8 is determined by the movement of pin 46 and the adjustment of cam 43, but the time interval between release of latches 9 and Ill is determined by the speed of -movement of sector gear 24 and the setting of cam 48.

When the major radius portion I 50 of cam 48 is positioned at a desired point, such as illus- .tratedinZ-Fig. i6, it: is in position to engage ;a:main

lever. fulcrum I 49 provided .on the :main lever 8. Inthispposition release of theprimary latch-pawl E34 and-slight counterclockwisemovement of the primary latch pawl causes release of the sec- .ondary latch IG prior to release of the primary latchst. This isbrought about as follows:

The spring I4 urges the pin 4.6 counterclockwise. Due to the retarding action'of .thestud'25 in slot I48 the left end of lever B is rocked :up until main lever fulcrum I49 contacts the cam portion I50. Slight counterclockwise rotation .of pawl 134 rocks the main lever B-aboutits fulcrum I49 to cause the extension 210 to strike pawl II and release latch II] due to the :force .ofspring I4 being greater than that of spring I46. 'Thus, with this adjustment of cam 48, the latch I0 never holds either shutter blade. The timing of the mechanism is such that're'lease pawl .ITI clears the latch It slightly before thehook 200 clears the latch 9. As soon as the hook'200 :clears latch 9 the springs 2 and 4 cause movement TOf the shutter blades I and 3 since neither latch restrains them. The springs 2 and 4 are of :substantially equal strength and operate against substantially equal load so that theshutterzblades I and fi-move at substantially equal speeds across the lenses. The exposure will, therefore, be very fast inasmuch as the apertures'I-35 and I36 flash past the lenses, the extent of exposure being controlled entirely by the overlapping of the tapertures as they move past thelenses (Fig. 21).

When the cam 43 is rotated to a slight extent counterclockwise from the positionshown in Fig.

6 the beginning of the spiral I52 is-presented for gear stud 25 engaging the main lever slot 148, said pin rotating the sector gear 24 and its pivot it] and driving a ratchet 230 through a ratchet pinion 26 (as will be explained later). The ratchet mechanism provides means for slowing :the movement of the sector gear so that an interval of time is provided between the release ofrla'tch 9 and'the release of latch II]. The radius "of cam it at this position is such as to permit the hook 12% to release latch '9 before thelever extension 2-!!! strikes release pawl l i to release 'latch IE. Thus the latch 9 releases both blades, blade I continuing to its end position where'its aperturesuncover the lenses, blade 3 moving first into contact withlatch it, then after a time'infterval moving to its end position. The exposure time interval may be increased to a maximum continuously adjustable position almost to the limit of the spiral I52.

When the cam 43 has been rotated to the position illustrated in Fig. 7, a notch 2313 in along interval earn 4? splined-to shaft 49 is brought into alignment with a cam follower end 233 on a long interval lever 28 (Figs. 10, ll, 12). As will be explained later, this action brings a long interval pawl 29into engagement with the'ratchet 230 in addition to an escapement pawl 2'5 which normally engages the ratchet 230. Thus gear 24 must overcome theslowing effect 'ofthe'twopawls through pin 48 from its set position toa position where its fulcrum I49 bears against the cam 48 to cause the extension 2 III to release the secondary latch I0. When the cam 48 is in this position at the smallest end of the spiral I52 a long interval of fixed duration elapses between the release of shutter blade I and the release of shutter blade 3.

When the cam 48 is rotated to the position shown in Fig. 8 the minor radius I56 is presented to the fulcrum I49, this minor radius being such that the lever 8 never comes to bear against cam 48 and movement of the sector gear 24 is arrested by the gear 24 striking a boss I54 before any tension can be brought to bear by extension 2I0 against pawl II to release the secondary latch I 0. This condition will remain static as long as the release lever I 6 is held in its depressed position. This position corresponds to the bulb position of a camera and continues as long as the lever I6 is held depressed. Upon release of the lever I6 spring I51 causes the lever I6 to move counterclockwise. The lever B is floating in a position such that a main lever stud I58 thereon is near the upper end of a slot 2I5 in the plate I43 and is in position to be struck by the tail 89 of lever I6 (Fig. 9). The movement of the lever 8 through this medium is sufficient to cause the extension 2I9 to release the secondary latch I and cause the blade 3 to end the time exposure, this action corresponding to the closing of a camera shutter by a bulb time exposure mechanism.

1 thus have, through the same sets of parts,

means for instantaneous exposure, means for infinitely variable fast exposure, means for a set, long exposure, and means for a manually controllable time exposure of lengthy extent.

Exposure speed adjustment Figs. 10 and 11 show the arrangement of the cams 41 and 48, the shaft 49 and a knob I42 together with an exposure speed dial I4I, the latter two items being visible in Fig. 1, from which a more comprehensive idea of the locavtion of the adjusting knob may be obtained. It

vment against the thrust of a friction washer I45 which tends to hold the assembly in its adjusted position. Immediately above the washer I45 the shaft is provided with a step enlargement which is journaled in an opening in the mounting plate I43. Immediately thereabove the shaft is provided with a second step that journals the primary latch pawl I34, which is retained in position by a third step in the shaft. The upper end of the shaft carries a hub 223 which is fastened to the shaft by a set screw 224, and the dial MI is fixed to the upper surface of the hub 223. The periphery of the dial carries figures and indicia on its upper surface which are visible through the arcuate window I44. The upper end of the shaft, after passing through the top plate 22I, is keyed to enter a key socket in the knob I42 which is retained in position by a screw 225 threaded into the end of the shaft. Rotation of the knob I42, therefore, rotates the cams 8 l 41 and 48, and the extent of rotation thereof is indicated by the dial indicia passing an index point 226 on the upper surface of the plate 22I. The indicia carried on the dial I4I indicate the fraction of a second of exposure, or other information relating to the exposure speed.

Escapement mechanism Fig. 12 further relates to the mechanism disclosed in Figs. 5 to 11 inclusive in that it discloses the complete escapement mechanism including.

the sector gear 24. In this figure, for clarity of illustration, the mounting plate I43 and the cams 41 and 48 are shown in dash outline. It will be seen that the sector gear 24 engages with the ratchet pinion 26 which is fastened to the upper surface and concentric with the escapement ratchet 239. When the portion of cam 48 including the major radius I59 and all but the minor radius is in position to engage the fulcrum I49 of the main lever 8 only one of two ratchet escapement pawls is engaging the teeth of the ratchet 238 to slow the movement of the sector gear 24. This primary escapement pawl is indicated by the numeral 21. It may be seen that the teeth thereof engage the teeth of the ratchet 239 and permit their release in timed steps rather than in a continuous uninterrupted movement. This type of escapement is well known in the art.

When the cams 49 and 41 are turned to permit the fulcrum point I49 of lever 8 to engage the cam 48 at a radius but slightly larger than the smallest radius portion of the spiral I52 the exposure is at a maximum time exposure of fixed duration with the shutter closing automatically at the end of the time. This is accomplished by mechanism disclosed in Fig. 12 in the position disclosed in Fig. 12. It will be seen that the long interval escapement pawl 29 is pivoted at 23I beneath one arm of the long interval lever 28 which is pivoted on a boss in plate I5 and secured with a screw 232 threaded into the mounting boss. The far end of the long arm of lever 28 is provided with a cam follower end 233 Which is adapted to engage the long interval notch 234 in cam 41. Thus the long interval escapement pawl 29 is brought into engagement with the teeth of the ratchet gear 230 by a tension spring I53 extending between the crank arm 235 of lever 28 and a boss 238 extending upward from the bottom plate I5. The arm 235 is urged against an eccentric screw 409, which may be rotated to adjust the engagement of pawl 29 with ratchet 230. The ratchet gear 239 now has to overcome the inertia of the pair of pawls 21 and 29 rather than the single pawl 21 during the movement of the sector gear 24. When the shaft 49 is rotated in either direction from this position the long interval escapement pawl 29 is removed from engagement with the teeth of the ratchet gear 230 and the ratchet gear has to overcome the inertia of the pawl'21 only, therefore the length of time required for the main lever 8 to pivot about the cam 48 is controlled entirely by the single escapement pawl 21. In this position the back of pawl 29 engages a pair of bosses 231 preventing the pawl from rocking into engagement with the ratchet 230.

Trip mechanism Referring to Figs. 5, 13 and 14 there is disclosed means whereby the release lever I6 is moved from the position illustrated in Fig. 5. the set position, to the position illustrated in acciqaeo Fig: 6;, the: release! position. This: mechanism comprises a shutter release button [.331 which is located in-and projects above-an opening innan extension of the top plate 22! indicated by the numeral 240. The button. [33. is provided with a flange 2M limiting outward. movement oft-he button. A buttonguide pin 242 extends downward into an opening in aboss 243..- ri'sing: up..- ward from the bottom plate. I1 5. The pin: 2242 passes through an opening in the short arm 01" atrip. lever 244 which is mounted upon a pivot Z45 pressed into the frame of the camera. The button I33 rests upon thehorizontal' short arm of lever 244, which is normally restrained in. its uppermost position by the spring I51. engaging the tail=80of lever L6 (Fig. 5). The long right end of lever It is provided-'witha rounded-knobs like projection 246 which engages the lower extremity of" thevertical long arm 24!- of the'trip lever; A screw 248 is threaded intothe portion 2400i the top plate andisremovable to permit the attachment of a standard release cable. Counterclockwise rotation of triplever 2M is li'miiuedby theinterierence of shutter case plate 5 witharm- 281. It may be seen from the foregoing and thedescriptionof the mechanism-in Figs. 5- to 12 inclusive that whenan accurately fast: exposure is desired the button I33 is depressed,- which action will cause release of both the-shutter blades. When a manually controlled timecx'posure is desired. the button [31%- is depressed, but due-to the inability of main lever '8 to -release the secondary latch It, the film will remain exposed to the light until button W3 is released, whereupon spring l'5'l'will cause lever it to return to its set position-and in so doing cause the tail 8'0- to engage the main lever stud 1-58 to release the secondary latch and end the time exposure.

Reset mechanism Figs. 15, 116 and. 17 illustrate the resetting mechanism for the camera. Fig. 15" should be studiedinv conjunction with Fig. 5; which, it-will be recalled, illustrates the mechanism in the set! position with the rear shutter blade having its aperturesin front of the-lenses and the-front shutter blade-held with its apertures-to the'l'eft ofthelenses by the latch 9. In this position the release lever pawl'l 3 is holding the primary latch pawl I34. The tab 203 is resting against the elbow of the release lever I6 I he opposite face of the tab 203 engages the tip of an arm 269 on a reset stop pawl '35 which is pivoted at 261 to the camera frame. A spring 18 is tensioned around the pivot 26! and has one end engaged against therear plate 262 of the camera and its opposite end hooked over the rear edge of the reset stop pawl I5. The spring 58, therefore, urgesa reset stop pawl tab 263 into engagement with a reset cam notch I30 provided in the surface-of a cam H 9 which is mounted upon a pivot 264 extending upward from" the bottom plate I5. When the release lever I6 is rocked to the position illustrated in Figs. 6 and 16 the releaselever pawl 13 is rocked clockwise and thetab 203 rocks the-reset stop pawl clockwise to disengageit from the cam notch I30 against the tension of thespring 18. The release lever pawl [21 is provided with a downwardly extending tab 261* which engages an. arcuate face 268..on the rightend of primary latch pawl I 34 which is moving counterclockwise.- Therefore, as long as. the primary latch pawl is released the reset stop pawl T5Jcannot'sree-engage-the resetcam notch I30.

'Theresetcam H 9: .is fixed, to .a. largeresehgear l d. which meshes with. a. small reset. gear 35 mounted upon ashaft. 33. extendingafromthe; bot;- tom plate [5 through. the-top: cover and: which has fixedtheretoaresetknob lfl (Fig. l), reset lmob may: now be turned counterclockwise and the resetting: of" the. shutter mechanism. will be accomplished: in one complete revoluti'omof the reset: gear 19 InII'ig. lfiit will be seen thatithe latches agiand lo: project through a. slot: 210 in= arear' shutter case plate 5 andiproject. towarda parallel front shutter case plate 5 Thelatches=-9 and l fl en gage the shutter blades: 1 and 3 which liebestween the plates 5121101 6; When the latches 9 and l-ii are released they may pivotclockwise-to permit the shutter: blades to-move fromnset posttion at the left end orthe slot between the plates and 6 to. their released position toward the right end" of the. slot.

The rear shutter case plate 5iis-providedi with-=2. slot-271:, the lower edge of which is pressedirear wardly to -form a. guideraili 21:2 extending rearwarolly f-rom. the surface of: the plate 5%- The guide rail 212 is engagedaby a downwardly turned tab 213 on the end of a reset lever 35, the tip of which, adjacent tab 27%, is'provided with a reset crank. finger. 21 i, projecting. into. the, space. between plates. 5; and B... and, engaged. insl'ot's. L60 and IE4 in the shutter blades.v The. reset. lever 35. overlies, thev shutter. release. mechanismand extends. toward the right end of the. camera where it is, pivoted. upon a pin 2J5 projecting. upward from the face of. gear 19; When the camerails set lever 35' occupies, the. position illustrated in Fig. 15.

The slots 1.60 and Hill in the.- shutter. blades, as will presently appear, are of such length; that upon termination of the exposure the. left; ends of the slotsin the. shutterloladesv arecloselyadjacent thefinger 214 .on the resetcrank. As soon as the exposureis completed, the release lever. i6 is returned to. itsinitial p.osition,. asindicated. in Fig. 15, permitting the tab. 261 of release lever pawlv l3 to bear against the .face. 268i of. pawl-13A by. action of a. spring-25.0 hooked ovenatab 251 on. lever. I6, tensioned aroundthe. hub. of pawl i3, and hooked over the edgeof pawl..l,3.. This readiesthe releaseleverpawl l3. to latch the primary latch pawl [34, but dueto. the engagement of the ,tabifi? with the.face;268 (Fig. 16;) it.-may not do. so, and the. resetstop. pawl.1-5.is.held:.in inoperative position.

In Fig. 17 the primary latch. pawl; 344s shown in dash lines atv the endof itsmovementcorrespending; to the illustration in Fig- 8,; Withthe release lever pawll 3. still heldin-clockwise position. It is alsdseen, in this figure thatthe-release lever. 1.6 has. returned to, its initial position and at the, termination of the exposure .thezreset lever 35..v (in. dash lines) still OGCupieSIitSSen-1903i:- tionwith the reset finger. 271.4.-attheright-endof the guidev rail 21 2. In this positionthe primary latch pawl reset stud 51 lies closely adjacentan edge of a. portion ofthe reset lever 35. Thenperatornow turns the reset-knob. 4'0 counterclockwise, thus rotating the reset, gear 19 clockwise. The'reset lever-35 is thus caused to bear against the stud- 51 to rockthe pawl i3 3 clockwise; As will be recalled, this causes repositioning-of the sector gear= 24 and the main lever 3 ta their set position duetstheinterconnection of these parts. During all of thistime the reset stop pawl l fi is held-fromengage'ment with theresetcam H9, exceptfor a brief intervalwvhen itis'moved-sti-lil 'the latch I into the slots I62 and I66.

readies latch 9 for engagement by primary latch farther clockwise as the tab 263 rides over the cam lobe 211. A reset crank offset I40 engages the primary latch pawl reset stud 51 (Fig. 17) as .the gear 19 completes substantially one-half of a revolution, whereupon additional rotation of gear 19 causes reset lever 35 to move the primary latch pawl reset stud to the position it occupies when the primary latch pawl I34 is in its set position. The reset lever 35 now begin to move away from engagement with the stud 51 but the pawl I34 is retained in set position by the re- .lease lever pawl I3 which has been moved counterclockwise by spring 259. Spring 18 now brings reset stop pawl 15 to bear against the face 215 of 'cam I I9 which is of greater radius than the bottom of the notch I30. The remaining semi-revolution of gear 19 merely returns the reset lever 35 to its position toward the right of the camera until the tab 263 drops into the notch I30. The

Shutter blades Figs. 18 to 25 inclusive illustrate the shutter blades and their operation. In Fig. 18 there is disclosed the front shutter blade I which is provided with a pair of apertures I35 having their left ends rounded and of such diameter as to permit the passage of light through the lenses without interference. The shutter is provided with a long slot I60 toward the left end, a short slot I6I near the center, and an edge slot I62 extending from the right of the center line toward the left end. An end notch I61 is provided in the lower right corner. The rear shutter blade 3, as disclosed in Fig. 19, is provided with "a'pair of apertures I36 having their right ends rounded and of the same radius as the rounded ends of apertures I35. The apertures I36 are substantially rectangular beyond the rounded ends and are longer than apertures I35. A slot I64 is adapted to overlie the slot I60. A slot I61 is in horizontal alignment with the slot I6I and an edge slot I66 is in horizontal alignment with the slot I62. The upper right corner is provided :with an end notch I68.

In Fig. 20 the blades I and 3 are shown in their relative position when pushed by the reset lever 35 to the left end of the channel they occupy between the blade case plates and 6. It will be seen that the finger 214 on the reset lever has engaged the left ends of slots I60 and I64 to push the blades completely to the left, which position corresponds to Fig. 1'7 illustrating the action of the lever (refer to solid lines of lever 35).

Tips of the latches 9 and I0 bear against the plates as the plates slide past them from right to left until the appropriate slots receive them. The light spring I38 urges the latch 9 into the slots I6I and I61, and the light spring I39 urges This pawl I34 and readies latch I0 for engagement by secondary latch pawl I I. It will be recalled that the offset I40 on reset lever 35 will now reposition the pawl I34 and associated mechanism so that book 200 will engage the tail of latch 9. Repositioning of primary latch pawl I34 will rock the main lever 8 clockwise to move its portion 2I9 away from the tail of latch pawl II permitting 12 spring I46 to return the pawl II into engagement with latch I0.

As soon as the pin 215 passes beyond dead center and substantially coincidental with the latching just described the reset lever 35 starts to ree tract. It will be observed in Fig. 20 that latch 9 is positioned in the left end of slot I61 which effectively prevents movement of the rear blade 3 as urged to the right by its spring 4. Latch 9 is at the right end of slot I6I so that the front blade I may move toward the right as urged by its spring 2 until it engages latch 9 (Fig. 21). The blades are therefore both held tensioned in the set position while the finger 214 retracts to the far right end of the slots I63 and I64 as the reset cam gear 19 completes its revolution to the position illustrated in Fig. 15. The blades are now in the set position with the camera lenses uncovered by the apertures I36 but covered by blade I whose apertures I35 are still to the left of the lenses. The blades are held in this position by latch 9 audit will be noted (Fig. 21) that latch I0 is slightly spaced from the left edge of slot I66 and is greatly spaced from the left edge of slot I62. Latch I0 is preferably spaced about of an inch from the left edge of slot I66 so that when the camera is set" all of the blade restraining force is provided by latch III which is held by positively retained mechanism including the pawl I34 and the pawl I3. Thus, if shaking. or jarring, or dropping of the camera occurs to such an extent as to cause the main lever B, or other connected mechanism to move sufficiently to release the secondary shutter latch pawl II, the secondary latch I0 nevertheless remains in operating position and will be re-engaged by the pawl II immediately after the transient disturbance.

If an instantaneous high speed exposure is desired and the fulcrum point I49 engages the major radius of the cam 48 to disengage the secondary latch I0 prior to disengagement of the primar latch 9, as soon as latch 9 is released there will be nothing to restrain the blades against movement to the right due to the effect of their springs (to be disclosed later). The two blades, therefore, flash past the lenses and expose the film at the highest speed possible, the duration of exposure being controlled by the width of the slots provided by the overlapping ends of the apertures I35 and I36 and the fixed tension of the springs 2 and 4.

If, on the other hand, an exposure of fixed duration of adjustable extent is required and the cam 48 has been positioned to present its spiral surface I52 to the fulcrum I49, the secondary latch I3 will be retained until a variable length of time has elapsed after latch 9 has been released. This action, illustrated in connection with Fig. 7, is further illustrated in connection with Fig. 22. It will be noted that latch 9 has been released first. thereby permitting the front blade I to spring entirely toward the right end of the camera until it is restrained from further movement at which point the rounded ends of the apertures I35 correspond with the rounded ends of the apertures I36 to provide a circular opening permitting the passage of light to the film. With the release of latch 9 by pawl I34, the movement of blade I pivots latch 9 clockwise against the tension of its spring I33, and the tip of latch 9 lightly presses against blade I. Latch I0, however, is still held by the latch pawl II and engages and prevents the rear blade 3 from moving more than the distance necessary for the lefted'ge of slot I 65 to engage latch Ill; as previously noted about of an inch. How ever, this slight movement does not affect the light transmitted as the extended apertures 536 require muchmore movement to enter the light path. Nor does this slight movement affect the timing asthe-movement is concluded before blade I uncovers the lenses. The primary function achieved by holding the blade 3- with latch 9 and not by latch I8, except when an exposure has been initiated, is to provide a locked mechanism protected from shock to insure dependable operation when it is initiated. Dependent upon the positioning ot the spiral I52, an interval of time elapses before latch IIl'relea-ses the'rear'blade Whenblade 3- is released it springs to the right to; the position illustrated in Fig. 23, causing the apertures I36 to move beyond the apertures I35 andthus terminate the exposure. Movement of blade 3 rotates latch IEI clockwise against the tensionof spring I35. and the tip of latch Id presses lightly against-blade 3*.

When a manually controlled time exposure is desiredcorresponding to the actions illustrated in Figsrd and 9-, the primary latch 9 is first released, as shown in Fig. 8, but due to the fulcrum I49 being opposite the minor radius portion. I56 in cam 68 the main lever 8 cannot release the secondary latch III. The blades will, therefore, rest in the position illustrated in Fig. 2-2 as long as the release button I33 is held depressed. When the button is relinquished release lever I6 yields to spring IE'I" and the portion of the release lever It strikes the main lever stud its to release the secondary latch It and complete the exposure.

Shutter blade pads and springs Atthe right end of the slot between plates 5 and iithere is provided a pair of pads of shockabsorbing material, such as a pad formed of inch thick vellum paper. There is a pad adjacent the upper corners of the blades and a pad Ila-adjacent the lower corners of the blades. It

will be noted that the blade I has its end notch l IS-Tin such position that the blade I is prevented from striking pad Md and only strikes the upper pad IE9. Similarly notch I83 in blade 3 causes blade 3 to strike the pad I'it only. This spacing of the pads and having them substantially independent of each other tends to eliminate thepossibility of shutter bounce of such an extent as to uncover the lenses after termination of the exposure. If the two blades struck the same pad there would be the possibility of the timed blows setting up sympathetic vibrations to such an extent as to bounce the rear shutter blade 3 back surhciently to uncover the lenses.

' In Figs. 18 and 19 it will be seen that blade I is-provided with a wide slot i853 which has a narrow extension It! at its top extending toward the left of the'blade.

I? in blade I.

Referring to Fig. 24 it will be seen that the front shutter blade case plate 6 is provided with an embossed ridge. I8? and av lower parallel ridge I88.which extend inwardly into the. space between the caseplates, 5; andyt, The rear plate his. pro.-

vided with matching ridges I89 and r941 respectively. The-adjacent surfacesof theridgesd'efme guides for the shutter blades I and3. Below the lower guides there is a wide space provided by stamping theplates outwardly and the slots I and I83 in the shutter blades lie within this-wide space. In Fig. 25-it will be seen-that a tongue I94. is stamped inwardly from plate 5, the tongue being provided with a pair of holes I 92' vertically spaced-the-same distance as the distance between the holes I82 and I85 in the shutter-blades. The spring 2 which operates the front shutterblade extends from hole F32 to the lowermost hole I 92 and the spring 4', which operates the rear shut ter blade 3 extends from hole I35 to the uppermost hole I52. The springs lie within the'slots I33 and" idtand do not bear against either shutter blade at any point except at their connecting ends. The ends of the springs passing through the holes 182 and I85 extendinto the extensions Hit and IiII respectively at certain periodsof the shutter operation. Fig. 25- illustrates thesprings 2 and s extendedas they would appear when the shutter blades are in set position toward the left. When blade I moves toward the right the hook on spring ii is still clearof the tront blade due to the extension I3-I.

There are thus provided operating springsof equal length which may be formed so as tohave very nearly the same resiliency and whichare tensioned to very nearly the same extent when the blades are set, and neither of which is subjected to frictional resistance by bearingv against any other part. When the high speed, orfastest, exposure is desired the two blades are released simultaneously by the latch e and dash past the lenses; maintaining, because of the matched springs, the aperture slot seen in Fig. 21. When an adjustably longer exposure is desired latch- It releases blade at a timed interval after latch releases blade i. There-fore, the slot provided by the apertures is wider or fully opened as determined by the setting of cam $3. In most instances the speed-of the blades is suflici-ently great to permit blade I to complete its movement and come to rest before blade 3 starts to cover the lenses.

Synchro-swifchv In Fig. 5 it will be noticed that between the latch It)v and the latch pawl I i there is an opening through the intermediate plate M3 through which a tab 32 projects to engage a shoulder I59- on the primary latch pawl I34. In Fig. 26 it will beseen that this tab 32 is mounted on the free endof'a short spring contact blade 3!. The spring contact blade 3| is retained by screws sos against the side of a projection 3m rising from the bottom plate I5. Insulators 302 insulate the switch blade 3I from the screws 39!; and the rear surface of the blade rests against a strip of insulating material 303. The strip 333 is mounted on the outer surface of a long switch blade 3b which is also insulated from the screws 3% by the insulators 3&2. It in turn rests upon a strip of in sulating material 3534 positioned between it and the projection 34.

The lower end of the tab 32 is mounted to blade 31 by a silver contact 305 which is in alignment with a silver contact 3% mounted on the long blade 3d,. The blade. 38 continues-on beneath the plate I43 and bears against an. eccentric screw 23 rising upward from the bottom plate I52 By adjusting the relative osition of theeccentrio. 2% the contacts 305-- and 306 are positioned .with respect to a visible scale.

serves two useful purposes.

at an adjustable distance from each other when the camera is in set position, as seen in Fig. 26, with the pawl I34 latched in position as in Fig. 5.

A wire 3I0 is soldered to blade (H and a wire 3 is soldered to blade 30. The two wires are passed through an insulating sheath 3I2 which passes forward to a position below and between the lenses where the wires 3I0 and 3H are connected to terminals 3I3 and 3I4 respectively, which pass through, but are insulated from, the bottom plate and are in position to receive wires (not shown) leading to a flash bulb socket and means for applying voltage to the flash bulb when the contacts 305 and 306 are brought together.

When it is desired to take a flashlight picture appropriate standard bulb and battery accessories are connected to terminals 3I3 and (H4 preparatory to flashing the bulb by closing contacts 305 and 306. The film is exposed by pressing the button I33 (Fig. 14). Downward motion of the button I33 moves the release lever I6 through the action of the trip lever 244. The tail 80 and the bent-down tab 204 (Fig. 13) normally hold the long switch blade 39 away from the eccentric screw 23 to a position sufiiciently far from blade 3|, that the contacts 305 and 306 cannot touch regardless of the position of other cooperating elements. Initial movement of lever I6, and hence of tab 204, permits the blade 30 to yield to its inherent tension and come to rest in its active position against eccentric screw 23 shown in Fig. 26. Additional movement of lever I6 releases the primary latch pawl I34 which starts to rock counterclockwise as described previously. Very slight angular movement of pawl I34 from its normal "set position moves the shoulder I59 sufficiently to permit blade 3| to yield to its inherent tension and bring contact 305 against contact 306. Additional movement of pawl I34 releases latch 9 and shutter blade I as described previously. The relationship between hook 200 and shoulder I59 is preferably such that contact 305 is brought to bear against contact 306 approximately of a second before hook 200 releases latch 9 for most flash bulbs. In this manner the flash bulb is ignited and permitted to come to full intensity of light before the opening of the lens apertures. Adjustment of the position of eccentric 23 by an attached slotted head 391 permits the second interval to be varied as desired. Preferably the head 30! extends through the bottom plate I in order that such adjustment may be made from outside of the camera, and may be calibrated Release of button I33 (Fig. 14) by the operator after completion of the exposure prompts spring I51 (Fig. 5) to move the lever I6 and its tab 204 counterclockwise, returning the switch blade 30 to its inactive position with the contacts open. In this manner the circuit is rendered safe for the operator to replace the flash bulb before resetting the shutter if he prefers without the danger of suffering severe burns from loading bulbs in hot circuits.

After the latch 9 is released pawl I34 continues to the end of its movement and may be returned by the reset mechanism. The resetting operation moves pawl I34 clockwise whereupon the shoulder I59 engages tab 32 and moves blade 3I against its tension to the set position.

It will be noted that the spring tension of the short blade 3| on the primary latch pawl I34 The obvious purpose is to bring the contacts together with suflicient pressure for reliable electrical contact when the primary latch pawl I34 permits the contacts to come together. The second and obscure purpose is to apply additional starting torque to the primary latch pawl I34. This is accomplished due to the tab 32 pressing against the shoulder I59 and tending to rotate the pawl I34 in the same direction that it is forced by the spring I4. and this additional force increases the acceleration of the escapement, or, in other words, aids in overcoming the inertia of the escapement when the shutter is tripped. The torque supplied by the switch blade 3| is applied only until the contacts close which, as has been noted above, is approximately 1 of a second before the shutter opens. Therefore the force of the spring blade M has no effect on the shutter timing which takes place after latch 9 is released. During the shutter timing period, i. e., from the release of latch 9 to the release of latch I0, the only force applied to the escapement mechanism is that of spring I4. It will be observed that there is no possibility of error due to manual interference with the timing of the switch since the timing is accomplished solely by the pawl I34 after the release lever I6 is operated. The primary latch pawl I34 positively times the opening of the shutters and the flashing of the bulb since both operations are entirely under its control.

I have thus provided photo-flash synchronization mechanism which is not in any manner affected by the operation of the shutter release button. An operator who depresses the button slowly will have exactly the same result as an operator who depresses the button rapidly. It will also be apparent that the use of pigtails is eliminated both for simplicity of construction and uniformity and dependability of operation.

Other mechanisms In Figs. 1 to 5 inclusive there are disclosed various other mechanisms, at least in part. For example, it will be seen that there is a knob 65 attached to an exposure counter dial. Mechanism provided within the camera rotates the dial to the proper extent each time that reset knob 40 advances the film. At the center of the camera to the left of knob 65 there is provided a view-finder device. To the left of center there is a knob I21 which (1) permits rewinding exposed film into the daylight loading magazine; (2) permits winding a predetermined length of exposed leader past the exposure apertures for economical loading of fresh fllm; (3) permits resetting the shutter without advancing the film; and (4) permits normal film advance sequence of alternately one frame and three frames automatically. At the extreme left of the camera there is a rewind knob 31 which operates in the usual manner to rewind the strip of film ma.- terial into its daylight loading magazine. In front of the window I44 there is a window through which is visible a focus tape I00 having indicia for indicating the distance from the lenses to the plane in sharpest focus. At the right of the window I44 there is a shield IIO adapted to move across and mask the indicia on the tape I00. At the left of the window I44 there is a shield II'I having indicia thereon for indicating the f-stop of the lens irises, shield III also moving across and masking the indicia on tape I00. The shields Ill and H0 are interconnected for simultaneous movement in opposite directions when a stop selector wheel 400 is rotated. The tape I00 is movable past an index point when a focus selector wheel 40! is rotated. The wheel 4M is rotated to focus the lenses. onthe subject by setting the scale read-v ing corresponding to the distance to the subject adjacent to the index point; the f-stop wheel is then rotated to set the selected f-stop value of the lens irises indicated by the'fscale onshield H1 opposite its index point. The shield moves simultaneously with the movement of the shield Ill and in the opposite direction. The two shields, therefore, uncover a variable portion of the tape- I00, the limits of which define the depth of field for that focalv distance and that particular stop value. The wheel dill adjusts the front element of the lenses to focus on the film located. adjacent the back of the camera; The wheel 400 controls the opening of the me ee for proper exposure under varying light conditions. These other mechanisms briefly mentioned herein may be more completely ascertained from my copending applications, Serial No. 754,962, filed June 16, 1947, now Patent No. 2,527,105, issued October 24, 1950, and Serial No. 754,963, filed June 16, 1947, now Patent No. 2,515,272,1ssued July 18, 1950.

It is to be appreciated that the instant disclosure is with respect to a stereoscopic camera having a pair of lenses. However, it will be apparent to any person skilled in the art that the shutter blades I and 3 might have single apertures therethrough so located as to admit light through a single set of lenses for the taking of ordinary photographs. I do not intend that this patent should be limited to a stereoscopic camera.

Having illustrated and described the preferred embodiment of the present invention, it should be apparent to those skilled in the art that the combination and various portions of the combination are subject to modification in detail and arrangement. Likewise, some one operation of the herein disclosed mechanism may be utilized without utilizin the others in cameras omitting some of the refinements of the present camera, or in cameras having other types of mechanism for achieving similar functions. All such modifications in detail and arrangement as come within the scope of the appended claims are considered to be a part of my invention.

I claim:

1. In a camera, a lens, a pair of shutter blades in closely adjacent, face-to-face relation adjacent said lens, guiding means maintaining said shutter blades in face-to-face relation and guiding said shutter blades for rectilinear movement transversely with respect to the optical axis of said lens, a pair of shutter blade springs individually attached to said shutter blades, said springs being tensioned between said shutter blades and fixed portions of said camera to effect independent movement of said shutter blades in the same direction to a released position, said shutter blades being of such weight with respect to the strength of their associated springs and said guiding means offerin such resistance to the individual blades that said blades move under the influence of said springs at substantially the same speed, manually operable resetting means including a lever engageable with both of said shutter blades simultaneously to move said shutter blades to a set position against the tension of said springs, said shutter blades each having an aperture therethrough, the aperture in one of said shutter blades being held at one side of said lens when said one shutter blade is in said set position and being in front of said lens when said one shutter blade has been moved to said released position, the aperture in theother of said shutter'blades being in front of said lens when said other shutter blade is in said set posi-- tion and being at the opposite side. of said lens:

2. In a camera, alens, a pair of shutter blades in closely adjacent, face-to-face relation adjacent said lens, guiding means maintaining said shutter blades in face-to-face relation and guiding said shutter blades for rectilinear movement transversely with respect to the optical axis of said lens, a pair of shutter blade springs individually attached to said shutter blades, said springs.

being tensioned between said shutter blades and fixed portions of said camera to effect independent movement of said shutter blades in the-same direction to a released position, said shutter blades being of such weight with respect to the strength of their associated springsand said guiding means offering such resistance to the individual blades that said blades move under the influence of said springs at substantially the same speed, manually operable resetting means including a lever engageable with both of said shutter blades simultaneously to move said shutter blades to a set position against the tension of said springs, said shutter blades each having an aperture therethrough, the aperture in one of said shutter blades being held at one side of said lens when said one shutter blade is in said set position and being in front of said lens when said one shutter blade has been moved to said released position, the aperture in the other of said shutter blades being in front of said lens when said other shutter blade is in said set position and being at the opposite side of said lens when said other shutter blade has been moved by its spring to said released position, a first latch engageable with both shutter blades to hold both shutter blades in said set position, a second latch engageable only with said other shutter blade to hold said other shutter blade in said set position independently of said first latch, and manually operable releasing means associated with said latches for releasing said latches independently of each other, said releasing means including adjustable means for effecting release of said second latch prior to release of said first latch or at variable time intervals subsequent to release of said first latch.

3. In a camera, a lens, a pair of shutter blades in closely adjacent, face-to-face relation adjacent said lens, guiding means maintaining said shutter blades in face-to-face relation and guiding said shutter blades for rectilinear movement transversely with respect to the optical axis of said lens, a pair of shutter blade springs individually attached to said shutter blades, said springs being tensioned between said shutter blades and fixed portions of said camera to effect independent movement of said shutter blades in the same direction to a released position, said shutter blades being of such weight with respect to the strength of their associated springs and said guiding means offering such resistance to the individual blades that said blades move under the 19 influence. of said springs at substantially the same speed, manually operable resetting means including a lever engageable with both of said shutter blades simultaneously to move said shutl tel blades to a set position against the tension of said springs, said shutter blades each having an aperture therethrough, the aperture in one of saidshutter blades being held at one side of said lens when said one shutter blade is in said set position and being in front of said lens when said one shutter blade has been moved to said released position, the aperture in the other of said shutter blades being in front of said lens when said other shutter blade is in said set position and being at the opposite side of said lens when said other shutter blade has been moved byits spring to said released position, a first latch engageable with both shutter blades to hold both shutter blades in said set position, a second latch engageable only with said other shutter blade to hold said other shutter blade in said set position independently of said first latch, and manually engageable releasing means associated with both of said latches including a constant speed escapement mechanism and pawl means operated by said escapement mechanism to release said latches, said pawl means comprising first pawl means to release said first latch shortly after initiation of operation of said escapement mechanism, second pawl means to release said References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,077,157 Pickard Oct. 28, 1913 1,117,637 Colardeau et al. Nov. 17, 1914 2,068,911 Goldhammer Jan. 26, 1937 2,218,248 Mihalyi Oct. 15, 1940 2,267,794 Kosken Dec. 30, 1941 2,328,677 Ringer et a1 Sept. 7, 1943 2,358,061 Drotning Sept. 12, 1944 2,364,652 Pollock Dec. 12, 1944 2,418,644 Hutchison et a1 "Apr. 8, 1947 2,553,015 Smith May 15, 1951 FOREIGN PATENTS Number Country Date 328,530 France May 4, 1903 444,698 France Aug. 14, 1912 410,306 Great Britain May 17, 1934 

